Cosart among pitchers optioned to minors

Jarred Cosart is expected to be a key member of the Astros' rotation in future seasons. (Karen Warren/Chronicle)

The Astros optioned righthander Jarred Cosart and three other top pitching prospects to the minor-league camp Wednesday morning.

Righthanders Cosart, Ross Seaton, Jose Cisnero and lefthander Brett Oberholtzer were all sent back to the minors to continue their development.

“It was a good experience,” said Cosart, who was acquired from the Phillies in the Hunter Pence deal in July 2011. “It was fun. I learned a lot. I’ll keep on going from here and hopefully get back here soon.”

“For all of them it’s just continuing to improve their approach, gain more game experience against upper-level talent,” Astros assistant general manager David Stearns said. “These are still young guys, all of them, with limited minor-league experience.

“They’ve all got very good arms. They’ve all got promising futures, but they still need time to gain some seasoning in the minor leagues.”

Cosart was considered to have an outside shot of making the opening day roster. But with the top contenders for the starting rotation starting to get stretched out, there aren’t enough innings at this point for everybody to get stretched out.

“He’s a guy that’s going to be a big part of our future,” Stearns said of Cosart. “He knows that and we know that.”

Despite the news, Seaton headed out of the clubhouse Wednesday morning happy about the experience.

Moreover, he was pleased to have met some of the major leaguers for the first time.

“It was just good being able to be around these veteran guys,” Seaton said. “They know how to play the game, and they show you how to act on and off the field. It’s been a good learning experience seeing how guys who have been around and done it carry themselves and how they pitch.”